Metal Surface and Process for Treating a Metal Surface

ABSTRACT

An article having a metal surface is treated to have one or more desired effects, such as desired functional properties or a desired cosmetic appearance. The surface is anodized to create an oxide layer having pores therein and a metal deposition process is performed to deposit multiple different metals within the pores. A pretreatment act, such as degreasing, chemical etching, chemical polishing, and desmutting can also be conducted on the surface prior to anodization. The surface can also be dyed, sealed, and polished.

BACKGROUND

1. Field

The present invention relates to treatments for a surface of an article and an article with such a treated surface.

2. Background

Many products in the commercial and consumer industries have metal surfaces. Such metal surfaces can be treated by any number of processes to create a desired effect, either functional, cosmetic, or both. One example of such a surface treatment is anodization. Anodizing a metal surface converts a portion of the metal surface into a metal oxide, thereby creating, a metal oxide layer. Anodized metal surfaces provide increased corrosion resistance and wear resistance. Anodized metal surfaces can be used to obtain a desired cosmetic effect. For example, pores in the oxide layer formed during anodization can be filled with metal or dyes to impart a desired color to the surface.

The cosmetic effect of metal surface treatments can be of great importance. In consumer product industries, such as the electronics industry, visual aesthetics can be a deciding factor in a consumer's decision to purchase one product over another. Accordingly, there is a continuing need for new surface treatments or combinations of surface treatments for metal surfaces to create products with new and different visual appearances or cosmetic effects.

BRIEF SUMMARY

In broad terms, a metal surface can be treated using a metal deposition process to create a desired effect. A method of treating a metal surface of an article can include anodizing the surface to create an oxide layer having pores therein, and performing a metal deposition process to deposit multiple different metals within the pores. The deposited metals can impart a color to the oxide layer. The oxide layer and/or the deposited metals can be dyed. The color of the dye can be the same or different than the color of the deposited metals.

The article can be an article of manufacture having a metal surface that has been treated so that the pores of the oxide layer are partially filled with a first metal and a second metal via the metal deposition process.

The metal surface can be an aluminum surface and the article can be a handheld device. The surface can be anodized using a sulfuric acid bath to create an oxide layer having pores. The oxide layer surface can be dried, and a metal deposition process can be performed to deposit metal such as nickel and tin within the pores. The oxide layer and deposited materials can be dyed, and the nickel and tin can be sealed within the pores.

Additional features of the invention will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the invention. Both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the embodiments as claimed.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated herein, form part of the specification and illustrate exemplary embodiments of the present invention. Together with the description, the figures further serve to explain the principles of, and to enable a person skilled in the relevant art(s) to make and use the exemplary embodiments described herein.

FIG. 1 is a flowchart of a surface treatment process in accordance with one embodiment of the present application.

FIG. 2 illustrates an enlarged perspective view of a portion of a surface that has been treated in accordance with one embodiment of the present application.

FIG. 3 illustrates a cross-sectional view of a portion of the surface of FIG. 2 following a metal deposition process in accordance with one embodiment of the present application.

FIG. 4 is a flowchart of a surface treatment process in accordance with one embodiment of the present application.

FIG. 5 is a cross-sectional view of a portion of the surface of FIG. 2 following a metal deposition process and a dyeing process in accordance with one embodiment of the present application.

FIG. 6 illustrates a plan view of a portion of the surface of FIG. 2 treated in accordance with one embodiment of the present application.

FIG. 7 is a flowchart of a process of surface treatment in accordance with one embodiment of the present application.

FIG. 8 is a flowchart of a process of surface treatment in accordance with one embodiment of the present application.

FIG. 9 is a flowchart of a process of surface treatment in accordance with one embodiment of the present application.

FIG. 10 illustrates a plan view of a portion of the surface of FIG. 2 treated in accordance with one embodiment of the present application.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying figures, which illustrate exemplary embodiments. Other embodiments are possible. Modifications can be made to the exemplary embodiments described herein without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not meant to be limiting. The operation and behavior of the embodiments presented are described with the understanding that modifications and variations can be within the scope of the present invention.

FIG. 1 is a high-level flowchart of an exemplary surface treatment process 8. Process 8 includes an act 10 of providing an article having a metal surface, such as a metal part having a metal surface. This process can be applied to a broad range of metal parts including, but not limited to, household appliances and cookware, such as pots and pans; automotive parts; athletic equipment, such as bikes; and parts for use with electronic components, such as housings or other components for laptop computers, housings or other components for handheld electronic devices, such as tablet computers, media players, and phones, and housings or other components for other electronic devices, such as desktop computers. In some embodiments, the method can be implemented on a housing for a media player or laptop computer manufactured by Apple Inc. of Cupertino, Calif.

Suitable metal surfaces include aluminum, titanium, tantalum, magnesium, niobium, stainless steel, and the like. A metal part including a metal surface can be formed using a variety of techniques, and can come in a variety of shapes, forms and materials. Examples of techniques include providing the metal part as a preformed sheet or extruding the metal part so that it is formed in a desired shape. In one example, the metal part can be extruded so that the metal part is formed in a desired shape. Extrusion can be a process for producing a desired shape in a continuous manner of indeterminate length so that the material can be subsequently cut to a desired length. In one embodiment, the metal part can be shape cast via any suitable casting process, such as die casting and permanent mold casting processes, among others. In one embodiment, the metal part can be formed from aluminum, such as extruded 6063 grade aluminum. In some embodiments, the metal part is made of an aluminum-nickel or aluminum-nickel-manganese casting alloy. The choice of any materials described herein can be further informed by mechanical properties, temperature sensitivity, or any other factor apparent to a person having ordinary skill in the art. In some embodiments, the metal part can include a plastic substrate with a surface layer of metal joined thereto.

Process 8 additionally includes an act 12 of performing an anodization process on the metal surface. Anodizing a metal surface converts a portion of the metal surface into a metal oxide, thereby creating a metal oxide layer. Anodized metal surfaces can provide increased corrosion resistance and wear resistance. An exemplary anodization process includes placing the metal surface in an electrolytic bath having a temperature in a range from about 18 to about 22 degrees Celsius. Hard anodization can be accomplished by placing the metal surface in an electrolytic bath having a temperature in a range from about 0 to about 5 degrees Celsius.

In one embodiment, anodizing act 12 can create a transparent effect to the metal surface. In this embodiment, the metal surface can be placed in an electrolytic bath that has been optimized to increase the transparent effect of the oxide layer. The electrolytic bath can include sulfuric acid (H₂SO₄) in a concentration having a range from about 150 to about 210 g/l, from about 160 and to about 200 g/l, from about 170 to about 190 g/l, or about 180 g/l. The electrolytic bath can also include metal ions that are the same metal as the metal surface. For example, the metal surface can be formed of aluminum, and the electrolytic bath can include aluminum ions, in a concentration of about less than 15 g/l or in a range from about 4 to about 10 g/l, from about 5 to about 9 g/l, or from about 6 to about 8 g/l, or can be about 7 g/l. A current is passed through the solution to anodize the article. Anodization can occur at a current density in a range from about 1.0 to about 2.0 amperes per square decimeter. Anodization can have a duration in a range from about 30 minutes to about 60 minutes, or from about 35 to about 55 minutes, or from about 40 to about 50 minutes, or can be about 45 minutes. The thickness of the oxide layer can be controlled in part by the duration of the anodization process.

In order to achieve an oxide layer with a desired transparency, the thickness of the oxide layer can range from about 10 microns to about 20 microns, or from about 11 to about 19 microns, or from about 12 microns to about 18 microns, or from about 13 to about 17 microns, or from about 14 microns to about 16 microns, or about 15 microns. Pores are formed during the anodization process and in one embodiment are spaced approximately 10 microns apart. The diameter of each of the pores can range from 0.005 to about 0.05 microns, or from 0.01 to about 0.03 microns. The above dimensions are not intended to be limiting.

Process 8 further includes an act 14 of depositing one or more metals within the pores of the oxide layer formed during anodization to impart a desired color below the surface and into the pores of the oxide layer. In one embodiment, following anodization the article is immersed in an electrolyte bath including an inorganic metal salt in solution or a combination of two or more different inorganic metal salts in solution. For example, the metal salts can include salts of nickel, tin, cobalt, copper, or any other suitable metals. In one embodiment, an electrolyte bath solution can be used that contains a package chemical such as “Top Alcolord ED” from Okuno Chemical Industries Co., Ltd. of Osaka, Japan, at a concentration of about 300 mL/L, nickel-sulfide at a concentration of about 50 g/L, boric acid at a concentration of about 30 g/L, and a package chemical such as “Top Alcolord ED Special Additive” from Okuno Chemical Industries Co., Ltd. of Osaka, Japan, at a concentration of about 8 g/L. The package chemicals can be an additive, which, for example, can stabilize the reaction within the electrolyte bath. The solution can be maintained at a temperature of about 25 degrees Celsius, for example.

An alternating or direct current is then applied to the electrolyte bath so that the metal ions of the salt come out of the solution and deposit as a metal in the base of the pores of the oxide layer. The voltage, frequency, and/or other characteristics of the current can be changed during act 14 in order to achieve a desired effect. For example, in one embodiment, an alternating current at a frequency of about 60 Hz and voltage of about 4V can be applied for about 30 seconds. The voltage of the current can then be increased to about 6V for about 30 seconds. Following this, the voltage of the current can then be increased to about 11V for a time ranging from about 30 seconds to about 15 minutes.

In some embodiments, multiple different metals (via different metal ions in the solution) are deposited within the pores of the oxide layer. For example, in one embodiment, nickel and tin are deposited within the pores of the oxide layer. The multiple deposited metals can be the same or different colors and can be the same or different colors from the metal surface or the oxide layer. The combination of metal colors can result in a surface having a desired color. In one embodiment, the deposited metals fill less than half the volume of each pore. The metal deposition act 14 can include performing a first metal deposition process to deposit a first metal within the pores of the oxide layer and performing a second metal deposition process to deposit a second metal within the pores of the oxide layer. The first and second metals can be different metals, such as nickel and tin for example.

For example, the electrolyte bath solution can contain concentrated sulfuric acid (H₂SO₄) at a concentration of about 15 g/L, tin sulfate (SnSO₄) at a concentration of about 8 g/L, nickel sulfate (NiSO₄) at a concentration of about 30 g/L, and tartaric acid (C₄H₆O₆) at a concentration of about 15 g/L. The solution can be maintained at approximately room temperature (e.g., about 23 degrees Celsius), for example.

In one embodiment, an alternating current at a voltage of about 4V can be applied for about 30 seconds. The voltage of the current can then be increased to about 6V for about 30 seconds. The voltage of the current can then be increased to a voltage that can range from between about 10V to about 11V over the course of about 30 seconds. The current can then be maintained at a voltage that can range from about 10V to about 11V for a time ranging from about 5 minutes to about 10 minutes.

FIG. 2 illustrates an enlarged view of a portion of a surface 16 treated in accordance with one embodiment of the present invention. Surface 16 includes an oxide layer 18 formed over a metal surface 20. Anodic cells 24 are formed within oxide layer 18 and include a pore 22 formed within each cell during anodization act 12 described above.

FIG. 3 illustrates a cross-sectional view of surface 16 following metal deposition act 14. As described above, surface 16 includes oxide layer 18 formed over metal surface 20 with multiple pores 22 formed within oxide layer 18. Following metal deposition act 14, one or more metals 26 are deposited at the bottom of each pore 22. For example, the embodiment of FIG. 3 illustrates two metals 26 a and 26 b deposited within each pore 22.

FIG. 4 is a high-level flowchart of an exemplary surface treatment process 28. Process 28 includes the acts described above of providing an article having a metal surface 20 (act 10), anodizing metal surface 20 to create oxide layer 18 having pores 22 (act 12), and depositing one or more metals 26 (26 a, 26 b) within pores 22 of oxide layer 18 (act 14). Process 28 further includes an act 30 of dyeing oxide layer 18.

By way of example, act 30 of dyeing oxide layer 18 can include dipping or immersing oxide layer 18 or the entire article in a dye solution in order to impart a rich color to oxide layer 18. As described above, oxide layer 18 is porous in nature, which allows it to absorb a dye into pores 22. In some embodiments, the particle size of the dye molecule is from about 5 nm to about 60 nm, or from about 15 nm to about 30 nm. The act of dyeing oxide layer 18 can include dyeing oxide layer 18 and/or deposited metals 26 within pores 22. In one embodiment, an organic dye is used to dye oxide layer 18. If suitable, an inorganic dye can be used to dye oxide layer 18. Any suitable combination of organic and inorganic dyes can be used. The color of the dye can be the same or different than the color of metal(s) 26 deposited within pores 22 of oxide layer 18. When at least two metals are deposited, the color of the dye can be different from either one or both of the metals.

In one embodiment, the dye solution can be maintained at a temperature in a range from about 50 to about 55 degrees Celsius and can contain a stabilizer to control the pH of the dye solution. A variety of colors can be achieved depending upon the particular dye composition, dye concentration, and/or duration of dyeing. A variety of colors for oxide layer 18 can be achieved by varying the dye composition, the concentration of the dye and the duration of dyeing based on visualization and/or experimentation. Color control can be achieved by measuring oxide layer 18 with a spectrophotometer and comparing the value against an established standard.

FIG. 5 illustrates a cross-sectional view of surface 16 following metal deposition act 14 and dyeing act 30. As described above, surface 16 includes oxide layer 18 formed over metal surface 20. Multiple pores 22 are formed within oxide layer 18. Following metal deposition act 14, one or more metals 26 (26 a, 26 b) are deposited at the bottom of each pore 22. Following dyeing act 30, dye 32 is also deposited within pore 22. FIG. 6 illustrates a plan view of a portion of surface 16 treated in accordance with the process described herein in which a particular appearance (e.g., color) has been imparted to surface 16 via deposited metals 22 and/or dye 32.

FIG. 7 is a high-level flowchart of an exemplary process 34 of surface treatment. Process 34 includes the acts as described above of providing an article having a metal surface 20 (act 10), anodizing metal surface 20 to create an oxide layer 18 having pores 22 (act 12) and depositing one or more metals 26 within pores 22 of oxide layer 18 (act 14). Process 34 further includes an act 36 of sealing oxide layer 18.

By way of example, act 36 of sealing oxide layer 18 can include immersing a metal surface in a sealing solution to seal pores 22. The sealing process can include placing oxide layer 18 in a solution for a sufficient amount of time to create a sealant layer that seals pores 22. The sealing solution can include, but is not limited to, nickel acetate. The sealing solution can be kept at a temperature in a range from about 90 to about 95 degrees Celsius. Oxide layer 18 can be immersed in the solution for a period of at least 15 minutes. In some embodiments, the sealing is performed using hot water or steam to convert a portion of oxide layer 18 into its hydrated form. This conversion allows oxide layer 18 to swell, thus reducing the size of pores 22.

FIG. 8 is a high-level flowchart of an exemplary process 38 of surface treatment.

Process 38 includes the acts as described above of providing an article having metal surface 20 (act 10), anodizing metal surface 20 to create oxide layer 18 having pores 22 (act 12) and depositing one or more metals 26 within pores 22 of oxide layer 18 (act 14). Process 38 further includes an act 40 of texturizing metal surface 20 before anodization (act 12).

Act 40 of texturizing metal surface 20 includes performing a texturizing treatment on metal surface 20 to create a textured pattern across the surface. This act can result in one or more decorative, structural, functional, or other effects on metal surface 20. In one such process, surface 20 can be texturized to roughen the surface, shape the surface, remove surface contaminants, or other effects. For example, the texturizing act can produce a desired tactile effect, reduce the appearance of minor surface defects, and/or reduce the appearance of fingerprints or smudges. In addition, the texturizing act can be used to create a series of small peaks and valleys. These peaks and valleys can impart a sparkling effect to the surface, which can in some instances make the surface appear brighter.

This texturizing process can be accomplished via one or more mechanical processes such as by machining, brushing, or abrasive blasting. Abrasive blasting, for example, involves forcibly propelling a stream of abrasive material, such as beads, sand, and/or glass, against the surface. Alternatively, the surface can be texturized through a chemical process, such as chemical etching. This process can involve the use of an etching solution, such as an alkaline etching solution.

The alkaline etching solution can be a sodium hydroxide (NaOH) solution. The concentration of the NaOH solution can range from about 50 to about 60 g/l, from about 51 to about 59 g/l, from about 52 to about 58 g/l, from about 53 to about 57 g/l, or from about 54 to about 56 g/l, or can be about 55 g/l. The NaOH solution can have a temperature of about 50 degrees Celsius. Surface 20 can be exposed to the NaOH solution for a time period that can range from about 5 to about 30 seconds, from about 10 to about 25 seconds, or from about 15 to about 20 seconds. These parameters are merely exemplary and can be varied. For example, other suitable etching solutions can be used, including, but not limited to ammonium bifluoride (NH₄F₂).

FIG. 9 is a high-level flowchart of an exemplary process 42 of surface treatment. Process 42 includes the acts as described above of providing an article having metal surface 20 (act 10), anodizing metal surface 20 to create oxide layer 18 having pores 22 (act 12), depositing one or more metals 26 within pores 22 of oxide layer 18 (act 14), dyeing oxide layer 18 (act 30), and sealing oxide layer 18 (act 36). Process 42 further includes an act 44 of polishing oxide layer 18. Act 44 can be conducted after sealing oxide layer 18 (act 36).

Act 44 of polishing oxide layer 18 can be accomplished through any suitable polishing methods, such as buffing or tumbling. This act can be performed manually or with machine assistance. In one embodiment, buffing can be accomplished by polishing oxide layer 18 using a work wheel having an abrasive surface. In one embodiment, oxide layer 18 can be polished via tumbling, which involves placing the article in a tumbling barrel filled with a media and then rotating the barrel with the object inside it. Polishing act 44 can impart a smooth, glassy appearance to oxide layer 18. For example, polishing act 44 can include tumbling the article in a barrel for about 2 hours at a rotational speed of about 140 RPM. In some embodiments, the volume of the barrel can be about 60% filled, and the media can be crushed walnut shells mixed with a cutting media suspended in a lubricant, such as a cream.

In some embodiments, polishing act 44 includes an automated buffing process, which can be a multi-stage process. An exemplary multi-stage process for automated buffing can include four stages. In a first stage, oxide layer 18 can be buffed for about 17 seconds with a pleated sisal wheel coated with an oil having coarse aluminum oxide particles suspended therein. In a second stage, oxide layer 18 can be buffed in a cross direction from the buffing of the first stage for about 17 seconds with a pleated sisal wheel coated with an oil having coarse aluminum oxide particles suspended therein. In a third stage, oxide layer 18 can be buffed for about 17 seconds with an un-reinforced cotton wheel coated with an oil having finer aluminum oxide particles suspended therein than the coarse aluminum oxide particles utilized in the first and second stages. In a fourth stage, oxide layer 18 can be buffed for about 17 seconds with a flannel wheel coated with an oil having finer aluminum oxide particles suspended therein than the coarse aluminum oxide particles utilized in the first through third stages. The type of abrasive particles, the size of the abrasive particles, the duration of the stage, and the material of the wheel described above for each stage, as well as the number of stages, are merely exemplary and can be varied.

Polishing act 44 can additionally or alternatively include the use of a chemical polishing solution. The chemical polishing solution can be an acidic solution. Acids that can be included in the solution include, but are not limited to, phosphoric acid (H₃PO₄), nitric acid (HNO₃), sulfuric acid (H₂SO₄), and combinations thereof. The acid can be phosphoric acid, a combination of phosphoric acid and nitric acid, a combination of phosphoric acid and sulfuric acid, or a combination of phosphoric acid, nitric acid and sulfuric acid. Other additives for the chemical polishing solution can include copper sulfate (CuSO₄) and water. In one embodiment, a solution of 85% phosphoric acid is maintained at a temperature of about 95 degrees Celsius. The processing time of the chemical polishing act can be adjusted depending upon a desired target gloss value. In one embodiment, the processing time can be in a range from about 40 to about 60 seconds. In addition, act 44 of polishing can be accomplished utilizing other methods that would result in polishing oxide layer 18 to increase the gloss of oxide layer 18.

In some embodiments, polishing act 44 results in a high quality surface with no orange peel, no waviness, and no defects. For example, all die lines, stamping marks, drawing marks, shock lines, cutter marks, roughness, waviness, and/or oil and grease can be removed from oxide layer 18 via polishing act 44. Similar treatment can be performed before the anodization act 12 described above.

Additionally, any of the above methods can include one or more further treatments on the metal surface 20 or oxide layer 18, such as rinsing, degreasing, desmutting, dyeing, sealing, polishing, texturizing, brightening, or anodization acts.

In some embodiments, a first portion of metal surface 20 or oxide layer 18 can be treated differently than a second portion of metal surface 20 or oxide layer 18 in order to create different patterns and/or visual effects. For example, in one embodiment, the first portion can be treated using the texturizing process described herein, and the second portion may not be subject to a texturizing act. In another embodiment, the first surface portion and second surface portions can be treated by different techniques. For example, the first surface portion can be subjected to abrasive blasting or chemical etching and the second surface portion can be subjected to another texturizing process described herein.

In addition, the two surface portions can be treated to have different degrees of scratch or abrasion resistance. For example, one technique can include standard anodization on one portion of the surface and the other technique can include hard anodization on another portion of the surface, or one technique can polish to a different surface roughness one portion of the surface compared to another technique performed on another portion of the surface. The different patterns or visual effects on surface 16 that are created can include, but are not limited to, stripes, dots, or the shape of a logo. In one embodiment, surface 16 includes a logo, wherein the first portion of surface 16 includes the logo and the second portion of surface 16 does not contain the logo. In other embodiments, the difference in techniques can create the appearance of a logo or label, such that a separate logo or label does not need to be applied to surface 16. For example, this can be accomplished through the use of a mask during one or more stages of the process. In one embodiment, a mask is applied to a first portion of the surface while a second portion of the surface undergoes one treatment process. The mask is then removed. A mask can then be applied to the second portion of the surface while the first portion of the surface undergoes a different treatment process.

In one embodiment, a first metal is deposited within the pores of the oxide layer on the first portion of the article, and a second metal is deposited within pores of the oxide layer on the second portion of the article. In one embodiment, first and second metals are deposited within the pores of the oxide layer on the first portion of the article, and a third metal is deposited within pores of the oxide layer on the second portion of the article. In another embodiment, first and second metals are deposited within pores of the oxide layer on the first portion of the article, and third and fourth metals are deposited within pores of the oxide layer on the second portion of the article. Each of the first, second, third, and fourth metals are different from each other. In any of these embodiments, the oxide layer on the first portion can be masked while the metal(s) are deposited within the oxide layer pores of the second portion. The oxide layer of the second portion can be masked while the metal(s) are deposited within the oxide layer pores of the first portion. For example, FIG. 10 shows a plan view of a portion of surface 16 having a first portion 16 a with a first appearance (e.g., one color) and a second portion 16 b with a second appearance (e.g., another color).

It is noted that the acts discussed above, for example the acts illustrated in the flowcharts of FIGS. 1, 4, and 7-9 are for illustrative purposes and are merely exemplary. Not every act need be performed and additional acts can be included as would be apparent to one of ordinary skill in the art to create a surface 16 having a desired effect. The acts can be reordered as desired. For example, act 44 of polishing the metal surface can be performed before or after the texturizing act 40 as well as before or after the anodizing act 12.

Example 1

In one prophetic example, a surface treatment process in accordance with one embodiment of the present application is applied to an aluminum housing for a portable media player. The housing is first rinsed to remove any debris. The housing is then placed in a chemical etching solution containing NaOH for approximately 20 seconds. After this process, the housing is removed from the solution and rinsed with clean water.

The housing is then anodized to create an oxide layer. The housing is placed in an electrolytic bath having a temperature of about 20 degrees Celsius. A current having a current density of about 1.5 amperes per square decimeter is passed between a cathode in the solution and the housing to create a build-up of aluminum oxide on the housing. This process is performed for approximately 40 minutes and can result in an oxide layer being formed on the surface of the housing. After this process, the housing is removed from the bath and rinsed with clean water.

The housing is then immersed in an electrolyte bath including nickel salt in solution. The electrolyte bath solution contains “Top Alcolord ED” from Okuno Chemical Industries Co., Ltd. of Osaka, Japan, at a concentration of about 300 mL/L, nickel-sulfide at a concentration of about 50 g/L, boric acid at a concentration of about 30 g/L, and “Top Alcolord ED Special Additive” from Okuno Chemical Industries Co., Ltd. of Osaka, Japan, at a concentration of about 8 g/L. The solution can be maintained, for example, at a temperature of about 25 degrees Celsius.

After the housing is immersed in the electrolyte bath, an alternating current at a frequency of about 60 Hz and voltage of about 4V is applied for about 30 seconds. The voltage of the current is then increased to about 6V for about 30 seconds. Following this, the voltage of the current is then increased to about 11V for about 5 minutes. After this process, the housing is then removed from the bath, rinsed with clean water, and dyed by dipping the article in an organic dye solution.

The pores of the housing are then sealed by placing the article in a solution of nickel acetate for about 15 minutes. After the pores of the housing are sealed, the housing is chemically polished by placing the article in a solution of 85% phosphoric acid for about 40 seconds. The housing is then rinsed with clean water and buffed for about 20 seconds with a pleated sisal wheel coated with an oil having coarse aluminum oxide particles suspended therein.

Example 2

In another prophetic example, a surface treatment process in accordance with one embodiment of the present application is applied to an aluminum housing for a laptop computer. The housing is first rinsed to remove any debris. A mask in the shape of a logo is applied to a portion of the housing to create an exposed portion of the housing and an unexposed portion of the housing. The housing is then sandblasted to create a desired texture on the exposed portion of the housing. After this process, the housing is removed from the solution, the mask is removed, and the housing is rinsed with clean water.

The housing is then anodized to create an oxide layer. The housing is placed in an electrolytic bath having a temperature of about 20 degrees Celsius. A current having a current density of about 1.5 amperes per square decimeter is passed between a cathode in the solution and the article to create a build-up of aluminum oxide on the article. This process is performed for approximately 40 minutes and results in an oxide layer being formed on the surface of the housing. After this process, the housing is removed from the bath and rinsed with clean water.

The housing is then immersed in an electrolyte bath containing concentrated sulfuric acid (98% H₂SO₄) at a concentration of about 15 g/L, tin sulfate (SnSO₄) at a concentration of about 8 g/L, nickel sulfate (NiSO₄) at a concentration of about 30 g/L, and tartaric acid (C₄H₆O₆) at a concentration of about 15 g/L. The solution is maintained at approximately 23 degrees Celsius.

After the housing is immersed in the electrolyte bath, an alternating current at a voltage of about 4V is applied for about 30 seconds. The voltage of the current is then increased to about 6V for about 30 seconds. The voltage of the current is then increased to about 11V over the course of about 30 seconds. The voltage is then maintained at about 11V for about 8 minutes. After this process, the housing is then removed from the bath and rinsed with clean water. The pores of the housing are then sealed by placing the article in a solution of nickel acetate for about 15 minutes.

The above processes can provide a metal surface having a desired effect, such as desired functional properties or a desired cosmetic appearance (e.g., a desired color). For example, in some embodiments, the processes can achieve corrosion resistance as well as a uniform color of the surface that does not flake or scratch through. The processes described herein also allow for a wide variation of visual appearances and cosmetic effects to be imparted to a metal surface.

The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

In addition, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. 

1. A method of treating a metal surface of an article comprising: providing an article having a metal surface; anodizing the metal surface to create an oxide layer on the metal surface, the oxide layer having pores therein; and performing a metal deposition process to deposit at least a first metal and a second metal within the pores of the oxide layer on at least a portion of the metal surface, wherein the first metal and the second metal are different metals.
 2. The method of claim 1, wherein the act of performing a metal deposition process includes performing a first metal deposition process to deposit the first metal within the pores and performing a second metal deposition process to deposit the second metal within the pores.
 3. The method of claim 1, further comprising: dyeing the oxide layer with a dye after performing the metal deposition process.
 4. The method of claim 3, wherein the act of dyeing the oxide layer includes depositing dye within the pores and dyeing the first metal and second metal after the first metal and second metal are deposited within the pores.
 5. The method of claim 3, wherein a color of the dye is different than a color of at least one of the first metal and second metal.
 6. The method of claim 3, further comprising: sealing the oxide layer.
 7. The method of claim 6, further comprising: polishing the oxide layer after sealing the oxide layer.
 8. The method of claim 1, further comprising: texturizing the metal surface before anodizing the metal surface.
 9. The method of claim 1, wherein a diameter of each of the pores is in a range from about 0.01 to about 0.03 microns.
 10. The method of claim 2, wherein the first metal is nickel and wherein the second metal is tin.
 11. The method of claim 2, wherein a color of the first metal is different than a color of the second metal.
 12. The method of claim 1, wherein the metal surface is formed of aluminum.
 13. The method of claim 1, the metal surface including a first portion and a second portion, wherein the first metal and the second metal are deposited within the pores of the oxide layer on the second portion, and wherein a mask is applied to the oxide layer on the first portion of the metal surface after the first metal and second metal are deposited.
 14. The method of claim 13, the method further comprising: performing a metal deposition process to deposit one or more metals within the pores of the oxide layer on the first portion of the metal surface, and wherein a mask is applied to the oxide layer on the second portion of the metal surface after the one or more metals are deposited on the first portion.
 15. A metal surface treated according to the method of claim
 1. 16. The method of claim 1, wherein the article is an electronic device housing.
 17. An article of manufacture, comprising: a metal surface including an oxide layer having pores that are at least partially filled with a first deposited metal and a second deposited metal.
 18. The article of claim 17, wherein the pores that are partially filled with the first and second deposited metals are sealed.
 19. The article of claim 17, wherein the first metal is a different metal than the second metal.
 20. The article of claim 17, wherein a color of the first metal is different than a color of the second metal.
 21. A method of treating an aluminum surface of a component for an electronic device comprising: providing a component for an electronic device having an aluminum surface; anodizing the surface in a sulfuric acid bath to create an oxide layer having pores therein; drying the oxide layer surface; performing a metal deposition process to deposit nickel and tin at the bottom of the pores; dyeing both the oxide layer and the deposited materials; and sealing the nickel and the tin within the pores.
 22. The method of claim 21, wherein the act of performing a metal deposition process to deposit nickel and tin within the pores includes a first act of depositing one of nickel and tin within the pores followed by a second act of depositing the other of tin and nickel within the pores.
 23. The method of claim 21, further comprising: polishing the oxide layer after sealing the oxide layer.
 24. The method of claim 21, wherein a color of the dye is different than a color of at least one of the deposited first and second metals.
 25. The method of claim 21, wherein the component for an electronic device is a housing for a handheld electronic device. 